Github user brianloss commented on a diff in the pull request:
https://github.com/apache/accumulo/pull/73#discussion_r54019025
--- Diff:
core/src/main/java/org/apache/accumulo/core/file/rfile/bcfile/Compression.java
---
@@ -147,25 +148,27 @@ public synchronized OutputStream
createCompressionStream(OutputStream downStream
},
GZ(COMPRESSION_GZ) {
- private transient DefaultCodec codec;
+ private transient AtomicReference<DefaultCodec> codec = new
AtomicReference<DefaultCodec>();
@Override
- synchronized CompressionCodec getCodec() {
- if (codec == null) {
- codec = new DefaultCodec();
- codec.setConf(conf);
+ CompressionCodec getCodec() {
+ DefaultCodec resultCodec = codec.get();
+ if (null == resultCodec) {
+ DefaultCodec newCodec = new DefaultCodec();
--- End diff --
If a bunch of threads all got to this point at the same time, they would
all create a new DefaultCodec. Only one will succeed on the compareAndSet
below, but the code is still potentially creating many DefaultCodec instances
which will get garbage collected.
Since isSupported returns true, I'm wondering if it's possible to simply
initialize the member variable at construction time, and then the
AtomicReference wouldn't be needed either? But maybe I'm missing something
obvious.
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